(i) Field of the Invention
The present invention relates in general to cushioning devices, in particular to a mattress comprised of an air cell mattress with a plurality of apertures extending through the base of the air cell mattress, a plurality of air channel mats residing beneath the air cell mattress, a top and bottom cover, and an air pump with a controller. The air pump communicates with the air channel mats to provide a flow of air to the bottom of the air cell mattress which flows upwardly through the plurality of apertures and through the top cover to remove moisture. These cushioning devices are typically used in a hospital setting for users that are severely disabled or debilitated and readily cannot move.
(ii) Description of the Related Art
Over the years various mattresses for use in therapeutic care and the prevention of pressure ulcers on the user of the mattress have been developed. Pressure ulcers are red areas or open sores on the skin, often accompanied by indications that the skin and surrounding tissue is in the process of dying and decomposing. Pressure ulcers are caused by restricted blood flow causing damage to the body""s soft tissue in areas where bone is close to the skin. Pressure ulcers, also known as bed sores, can occur over any boney part of the body such as the heels, hips and back. Users who are severely disabled, diabetic or debilitated and cannot move are ideal candidates for developing pressure ulcers. These users are apt to lie or sit motionless in one position for long periods of time (hours). The major causes of pressure ulcers include (1) oxygen and nutrient starvation of the soft tissue; (2) pressure; (3) friction and skin shear; (4) excess moisture or moisture build-up at the skin; and (5) heat build-up in the tissue. Pressure at the user-mattress interface can constrict capillary blood flow due to soft tissue deformation and starve body tissue of oxygen and nutrients. The starvation of the tissue causes the tissue to began to die and decompose, causing the formation of a pressure ulcer.
While the interface pressure is very important, other factors also contribute to developing pressure ulcers. Friction and skin shear forces intensify the damaging effects of interface pressure. Friction results in abrasion damage to the skin surface. Skin shear is the horizontal force between the user and the mattress surface that produces tearing forces within deeper tissues. Skin shear can occur when a user is positioned or slides on a bed surface, stretching and damaging skin, connective-tissue, muscle and blood vessels. Excess moisture or moisture build-up at the user-mattress interface can be absorbed through the skin and possibly result in over-hydration of the skin. Over-hydration of the skin dramatically reduces soft tissue strength and increases the potential for friction/shear damage. Excess moisture on the mattress also raises the drag friction of the user-mattress interface due to liquid surface tension and can greatly increase friction and shear damage. Another factor contributing to the development of pressure ulcers is heat build-up in the tissue. Elevated tissue temperatures increase cellular metabolism and the subsequent need for oxygen and nutrients. Typically, the prior art mattresses designed to prevent pressure ulcers employ some type of air cell mattress wherein the individual air cells communicate with one another so as to evenly distribute the supporting force over the body of the user of the mattress. While the use of mattresses that provide a uniform supporting force reduces the possibility of developing pressure ulcers, other factors need to be addressed in order to further diminish the possibility of a user developing pressure ulcers.
For example, excess moisture or moisture build-up at the user-mattress interface can result in over-hydration (or maceration)of the skin along with an increase in the friction and skin shear forces experienced by the user, which greatly enhance the potential for developing pressure ulcers. To overcome the excess moisture build-up, prior art mattresses have employed methods of providing a flow of air through the mattress and along the user-mattress interface to remove any built-up moisture and minimize the potential for moisture to build-up. These mattresses included the use of an air pump to supply a flow of air to an air distribution member residing beneath the mattress which flows between the air distribution member and the mattress and then upwardly through the mattress to the user-mattress interface. These prior art mattresses use a single air distribution member to provide the flow of air to the mattress. However, these mattresses had a drawback in that, the use of a single air distribution member does not provide the flexibility to custom tailor the flow of air to different parts of the mattress to provide different levels of comfort and moisture removal for the user of the mattress.
Typical prior art mattresses also employ a single air pump to supply air to both the air cells and the air distribution member. The use of a single pump to provide air to the air cells of the air cell mattress and to provide a flow of air to the mattress air distribution member to remove moisture increases the complexity and cost of the air supply system and prevents the use of other manufacture""s air cell mattresses. The complexity of the air supply system for both the mattress air cells and the air distribution member may also be difficult for a user to understand and control.
Some prior art mattresses utilize air from the air cells to provide a flow of air from the mattress to remove moisture. A typical mattress of this type uses low air loss air cells wherein the air cells are constantly venting a small amount of air out of the air cells as new air is being continuously pumped into the air cells. The air venting from the air cells provides the air flow to the mattress to remove the moisture. Additionally, other mattresses systematically inflate and deflate some of the air cells of the air cell mattress in order to relieve pressure on the user of the mattress. The deflation of the air cells provides an exhaust flow of air that is routed from the mattress to remove moisture therefrom.
Some prior art mattresses also utilize drainage holes in the mattress to remove large amounts of liquid that may be excreted by a user of the mattress, such as urine. While this aids in the removal of the liquid moisture, it does not remove moisture vapor and allows for a potentially unsanitary and non-hygenic mattress.
The use of this type of mattress requires the mattress to be cleaned and disinfected after having been contaminated.
The present invention overcomes shortcomings of prior art mattresses by providing a cushion that provides a uniform supporting force over a large area, an air channel mat for supplying air to the mattress to dry moisture vapor, and a cover that provides a smooth surface for the user to lay on that is vapor permeable and liquid impermeable. Furthermore, the present invention provides for a plurality of air channel mats that are supplied with a flow of air from an air pump that can selectively control which parts of the mattress are supplied with a flow of air to dry moisture vapor.
An effective therapeutic mattress that minimizes the possibility of pressure ulcers will (1) distribute pressure as evenly as possible along a user""s body minimizing or eliminating the potential of soft tissue deformation; (2) have a low friction user-mattress interface that minimizes the skin shear forces; and (3) actively removes excess user-mattress moisture.
The moisture drying mattress is comprised of at least one cushion that has opposite top and bottom surfaces and a plurality of apertures that extend through the cushion from the bottom surface to the top surface. An air channel mat is positioned below the cushion. The air channel mat is adapted and dimensioned to fit beneath the cushion and support the cushion bottom surface in a spaced relation above a bottom base of the mat to thereby form an air channel between the cushion and mat through which air can flow. An air pump is provided for selectively supplying a flow of air to the air channel mat. A controller is provided to control the flow of air to the air channel mat. A cover encases the air channel mat and the cushion.
In the preferred embodiment, the cushion is an inflatable air cell mattress comprised of a plurality of air cells. The air cells are interconnected to permit air flow between the air cells and are preferably cubic in shape with a domed top. The inflated air cell mattress provides a uniform supporting force for the user of the mattress to minimize the pressure concentrations on the user. The distribution of the supporting force helps to prevent the occurrence of pressure ulcers. A plurality of apertures are provided in the cushion that extend through the base sheet and top sheet of the air cell mattress but do not communicate with the air cells. The apertures provide a path through which air can flow from the air channel mat upwardly through the apertures and between the air cells and through the cover to remove moisture or dry the moisture vapor.
In the preferred embodiment, the air channel mat is a plurality of air channel mats that are each dimensioned and adapted to fit beneath a portion of the cushion and support the cushion bottom surface in a spaced relation above the base of the air channel mat. The air channel mats each have a peripheral edge separating opposite top and bottom surfaces of the base. An air supply connector is connected to each air channel mat along its peripheral edge. A plurality of projections extend upwardly from the base top surface of each air channel mat and engage with the cushion bottom surface to support the cushion bottom surface in a spaced relation above the base top surface and create a channel into which air can flow between the air channel mat base and the cushion bottom surface. Preferably, each air channel mat is also provided with a skirt that extends along a portion of the air channel mat peripheral edge. The skirt extends over the air supply connector and along a portion of the peripheral edge on both sides of the air supply connector. The skirt extends inwardly from the peripheral edge to cover a portion of the top surface of the base and the projections that extend upwardly from the base. The skirt serves to secure the air supply connector to the air channel mat and prevents the flow of air to the air channel mat from escaping along the portion of the peripheral edge with the skirt.
In the preferred embodiment, the air pump has a plurality of air outlets, with each outlet being controlled by a valve that is selectively positionable between opened and closed positions. The outlets are connected with the air supply connectors of the air channel mats, with each outlet being associated with one air channel mat and providing a flow of air from the air pump to the associated air channel mat when in the opened position. When the valves are in the closed position they prevent a flow of air from the air pump outlets to their associated air channel mats. The valves thereby allow a user to selectively choose which air channel mats receive a flow of air from the air pump.
In the preferred embodiment, the air pump includes an air supply controller that controls the valves and the air pump and has a plurality of selectively adjustable inputs, the inputs controlling the opening and closing of the valves and the operation of the air pump. The inputs control a cyclic opening and closing of the valves for predetermined periods of time. The selectively adjustable inputs thereby enable a user to custom tailor the air flow to the mattress and the subsequent moisture removal.
In the preferred embodiment, the cover is dimensioned and adapted to enclose the cushion and the air channel mats. The cover has a top sheet with a peripheral edge and a bottom sheet with a peripheral edge. The top and bottom sheets are connected together along portions of their peripheral edges, leaving an opening between the peripheral edges that provides access to an interior of the cover between the top sheet and bottom sheet.
Preferably, the bottom sheet has opposite top and bottom surfaces. The bottom sheet top surface has a plurality of pockets dimensioned and adapted to receive the air channel mats. The pockets are comprised of a U-shaped frame having an outer peripheral edge, an inner peripheral edge, and a margin extending between the outer and inner peripheral edges. The outer peripheral edge is secured to the bottom sheet top surface and the frame margin of the pocket overlaps a portion of the top of the air channel mat, thereby holding the air channel mat in the pocket. A portion of the air channel mat beneath the frame opening is exposed to the cushion bottom surface so that the mat projections engage with the cushion bottom surface to support the cushion bottom surface in a spaced relation above the air channel mat base.
Preferably, each pocket separates each of the air channel mats and forms a seal between the pocket and the cushion bottom surface. The seal directs the flow of air from the air pump through the air channel mat and then upwardly through the apertures in the portion of the cushion that is above the air channel mat, enabling the flow of air to be directed to the desired portion of the cushion.
In the preferred embodiment, the top sheet of the cover has a top surface, upon which the user will interface with the mattress, that is both vapor permeable and liquid impermeable. The top sheet is comprised of a nylon sheet laminated to a urethane sheet. The nylon sheet is above the urethane sheet so that a user of the mattress will interface with the nylon sheet and the urethane sheet is positioned between the nylon sheet and the cushion top surface. The laminated top sheet allows moisture vapor to permeate both into and out of the cover and prevents liquid on the top surface of the cover from entering the mattress and contaminating the cushion and air channel mats. The use of a nylon sheet as the interface between the mattress and the user reduces the friction between the cover and the user and thereby minimizes the possibility of the user developing pressure ulcers from friction or skin shear. Additionally, by utilizing a flow of air through the cover top sheet to remove the moisture vapor from the mattress-user interface, the user""s skin is less likely to over-hydrate (maceration) and as a result the soft tissue is strong enough to reduce the potential for friction and/or skin shear damage.
The moisture drying mattress of the present invention overcomes the disadvantages of the prior art. The use of a plurality of air channel mats that can be selectively supplied with a flow of air from an air pump allows the user to selectively choose which portions of the mattress receive the air flow The use of a cover having a top surface upon which the user will interface that is made of a nylon sheet laminated to a urethane sheet keeps liquids out of the mattress while allowing the air flow within the mattress to flow through the cover and remove moisture. The nylon surface provides a smooth, low friction surface upon which the user interfaces with the mattress and reduces the risk of damage to a user""s skin. Additionally, the removal of moisture from the user-mattress interface will also remove heat from the user""s skin via evaporative cooling and, accordingly, reduce the risk of developing pressure ulcers. The use of an air mattress that distributes a supporting force over the entire portion of the user""s body that is in contact with the mattress minimizes or eliminates the potential of soft tissue deformation and further reduces the possibility of developing pressure ulcers.